Insole

ABSTRACT

The invention concerns an insole for footwear. The insole comprises a liquid-filled sole with a top sheet and a back sheet between which is formed at least one chamber with liquid. On top of the liquid-filled sole there is provided a net. The net creates a spacing between the top sheet and the foot, and the net is capable of containing air absorbing moisture from foot perspiration. By using a net on top of a liquid-filled sole it is achieved that the foot perspiration formed because of frictional heat and muscle contractions when using liquid-filled soles is more easily contained in the net and more easily conducted around in the net along the plane of the net as a pumping effect of air in the net arises when the liquid-filled sole is imparted movement by the foot.

BACKGROUND OF THE INVENTION

The present invention relates to a liquid-filled insole for footwear.

The invention also concerns a method for making an insole for footwear,the sole at least comprising a support for the foot in the footwear, andwhich sole in addition comprises a net of threads disposed on top of thesupport, the net creating a distance between the support and the foot inthe footwear, and where net is joined with the support along an outeredge of the net.

DE 296 03 914 describes an insole of this type. The insole comprises asupport at the heel of the foot in the footwear. The support consists ofan elastic material that may be compressed for relieving the heel. Thesupport may be made of a foam synthetic or of cork. On top of the centrearea of the support a net is disposed. The net consists of two layer ofsynthetic threads which are woven or knitted. The net is fastened to thesupport at the heel by welding. The net extends from the heel of thefoot and forward right up to the toes of the foot in the footwear. Fromthe heel and further under the metatarsus, under the ball of the footand under the toes there is no support under the net. The net gives thepossibility of air passing transversely of the net between the foot andthe support of the insole and the inner sole in the footwear,respectively.

This sole implies the possibility of relieving the heel and of supplyingair to the foot in the footwear. The insole has, however, somedrawbacks. The net is fixed in relation to the support and in relationto the insole of the footwear. This means that air flow in the netdepends on differences in moisture of the air contained in the net. Thiscauses the air flow in the net to be very limited, implying that theparts of the foot developing the largest amount of moisture are onlynegligibly supplied new air. Furthermore, the net does not extend overall of the width of the sole at the heel and the metatarsus of the footin the footwear. This implies that no exchange of air can take placelaterally of the net. The comfort of the foot in the footwear istherefore very limited even though the foot rests on a net establishinga distance between the foot and the support and the inner sole of thefootwear, respectively.

In U.S. Pat. No. 5,067,255, a liquid-filled insole is disclosed forcushioning and impact absorption. The insole may be covered by, forexample, a fabric or leather.

Liquid-filled soles are intended to reduce and to vary the load on thefoot when walking and standing. Especially by standing work, theincreased movement of the foot caused by liquid-filled soles gives riseto increased excretion of foot perspiration. This causes more people torefrain from using liquid-filled soles in spite of the ergonomicadvantages by using the soles.

It is the purpose of the present invention to provide a liquid-filledsole where the inconvenience by using liquid-filled soles is greatlyreduced.

This purpose is achieved with an insole which is peculiar in that thesupport is a liquid-filled sole with a top sheet and a back sheetbetween which is formed a chamber containing liquid, that the outer edgeof the net is joined with the top sheet and the back sheet, and that thenet at least extends from an area at the heel of the foot to an area atthe ball of the foot in the foot wear and at least extends over thewhole width of the sole.

The method according to the invention is peculiar in that a top sheetand a back sheet are welded together at the outer edges in that achamber containing liquid is established between the two sheets, andthat the net in a subsequent step is welded together at the edge area ina position superposing the top sheet.

By providing a net on the liquid-filled sole, the increased footperspiration arising from the use of liquid-filled sole may more easilybe conducted away from the underside of the foot.

By laying the net upon a sole containing liquid between a top sheet anda back sheet, the possibility of moving the net relative to themovements of the foot is established This implies that as soon as thefoot is moved, the net will also be moved, and this creates an air flow,not only transversely of the net, but also longitudinally of the net.This means that air with high humidity contained in the net, e.g.typically under the heel or under the ball of the foot, will be passedto other parts of the net, e.g. under the metatarsus or under the toeswhere the air humidity is not so high. This causes the air humidity tobe lesser locally as the moisture is distributed over all of thelongitudinal and preferably also trasversal extension of the net.

Due to the fact that net provided on liquid soles improves the abilityof the net to create ventilation between the foot ent the underlyingsole, the net improves the function of the liquid filled sole.

By making the insole in two steps as defined by the method according tothe invention, it is possible to achieve a plane net upper sidesimultaneously with increasing the height in the chamber. Hereby therelief and the liquid support of the foot will be considerablyincreased.

Preferably, the net will extend over all the transverse extension of thesole. Hereby the outermost part of the net along the edge area will besituated outside the limits of the foot. The part of the net locatedoutside the foot thus has a free upper side enabling discharge of airwith great humidity from the interspace under the foot simultaneouslywith fresh air with low humidity from other parts of the footwear may beconducted into the interspaces in the net under the foot. The free edgearea is thus advantageous in enabling an increased ventilation and airflow in the net of the sole.

In a preferred embodiment, the insole is peculiar in that the netcomprises a coarse net and a fine net, that the coarse net consists ofthreads with a given greater thickness T, that the fine net consists ofthreads with a given lesser thickness t less than the thickness T, andthat the coarse net is disposed between the top sheet and the fine net,and that the fine net is disposed on top of the coarse net.

Depending on the weaving, a coarsely woven net with thick threads iscapable of containing more air and thereby more humid air than a finenet. However, the coarsely woven net also has a more rough surface. Thismay give rise to greater discomfort for the foot in the footwear, andmay also imply more wear on stockings or socks on the foot. A finelywoven net cannot contain so much air but in the opposite is morecomfortable to tread on, and the risk of socks being broken is less. Bylaying a coarsely woven net lowermost adjacent to the top sheet and amore finely woven net facing the foot on top of the coarse net, theadvantages of the coarse net will be combined with the advantages of thefiner net without reducing the possibility of air to be conductedlongitudinally of the sole.

In a further preferred embodiment, the insole is peculiar in that amoisture absorbing fabric coating is provided between the top sheet andthe net.

By providing the top sheet with a moisture absorbing fabric coating, theairborne moisture arising in the net from the foot in the footwear willbe absorbed by the fabric coating. This means that the moisture isconducted away from the foot, down through the net where the moisture isdistributed longitudinally of the net each time the foot is moved, andfurther down to the fabric coating on the top sheet. The moisture willthus always be conducted away from the foot. When the net, when providedon a liquid sole, is capable of distributing the humid air over all ofthe longitudinal extension of the net, then the fabric coating will alsoabsorb the moisture over all of the length of the fabric coating, saidlength at least being the same as for the net.

DESCRIPTION OF THE DRAWING

The invention will then be described in more detail with reference tothe accompanying drawing, where

FIG. 1 is a view from above of an insole according to the invention,

FIG. 2 is a transverse sectional view of a first embodiment of the sole,

FIG. 3 is a transverse sectional view of a second embodiment of thesole,

FIG. 4 is an enlarged sectional view of a part of the first embodimentof the sole when in use,

FIG. 5 is a view from above of a possible weaving of the threads in thenet of the sole,

FIG. 6 is an enlarged sectional view of a part of the third embodimentof the sole when in use,

FIG. 7 is a sectional view of a possible weaving of the threads in thenet of the sole, and

FIG. 8 is a transverse sectional view of an embodiment of the soleformed by a method according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a net 1 provided on a liquid-filled sole 2 (see FIG. 2).The liquid-filled sole is situated under the net. The liquid-filled sole2 comprises at least a top sheet 3 and a back sheet 4 (see FIG. 2),preferably of plastic, which are joined along outer edges 5 of the sole,along a line 6 transverse to the sole between an area 7, where the ballof the foot rests, and an area 8, where the toes rest, as well as atpoints 9 in an area 10 between an area 11 for the heel of the foot andthe area 7 of the ball of the foot. The joint at the points 9 form flowbarriers for the liquid in the liquid-filled sole 2 so that the flow ofthe liquid between a rear part and a front part of the sole occurs witha certain sluggishness. Joining of the top sheet and the back preferablytakes place by high frequency welding.

In the shown embodiment, the net 1 disposed on top of the top sheetextend over the whole length L of the sole and over the whole width W ofthe sole. In alternative embodiments, the net may only extend a part ofthe length of the sole, e.g. from the area 10 at the heel to the area 7for the ball of the foot to the line 6 formed between the area 7 for theball of the foot and the area 8 for the toes.

FIGS. 2 and 3 show schematically a first embodiment of a sole accordingto the invention and a second embodiment of a sole according to theinvention, respectively. FIG. 2 shows a liquid-filled sole 2 comprisinga top sheet 3 and a back sheet 4. Between the sheets 3,4 is formed achamber 12 filled with liquid. The top sheet 3 and the back sheet 4 arejoined along the edges 5 of the sheets. A bead 13 extends into thechamber 12 and stems from welding together of the edges 5 of the sheets3,4, where some of the sheet material from the edge of the sheets hasflowed inward toward the chamber.

The net 1 is placed on the top sheet 3. The net 1 extends over the wholewidth W of the sole. The net 1 is joined along an edge of the net withthe top sheet, at least. The net is also joined, preferably by welding,with the top sheet. The net is flexible upward and downward to a degreeat least corresponding to the occurring compression of the chamber sothat the net may follow the movements of the sole. The net can be madeof different synthetic as well as natural materials like plastic andcotton, but are preferably made of plastic. Several plastic materialsare suitable for making the net, for example PVdC, PU, EVA and PVCprovide the possibility of welding the net to the top sheet by means ofhigh frequency welding.

FIG. 3 shows a second embodiment where between the top sheet 3 and thenet 1 is provided a moisture absorbing fabric coating 14. The fabriccoating 14 is capable of absorbing moisture and is e.g. made of cotton.The fabric coating 14 is welded together with the net 1 along the edgesof the net and the top sheet 3, respectively. The moisture from footperspiration conducted down through the net 1 from the upper side of thenet 1 where the foot rests (see FIG. 4), is then absorbed by the fabriccoating 14. Thereby the moisture in the air is considerably reducedbetween an upper side 15 of the net and an underside 16 of the net. Thisembodiment is specially suitable for users with large excretion of footperspiration.

FIG. 4 shows a net 1 upon which a foot 17 with a sock 18 or stockingrests. The net 1 is situated between the top sheet 3 and the foot 17 andcreates a distance D between the top sheet 3 and the foot 17. The net 1is made of threads 19 which in the shown embodiment are woven. Thethreads 19 may also be knitted or may be non-woven, The have a diameterc. In meshes 20 (see FIG. 5) between the threads 19 in the net 1 thereis air, and moisture from foot perspiration from the foot sole may bediffused down in the air between the meshes 20 between the threads 19.The meshes have width and length E, respectively. The distance D betweenthe top sheet 3 and the foot 17 is typically between 0.3 and 5.0 mm. Thedistance D and the size E of the meshes depend on the diameter c of thethreads 19 and on how the threads 129 are woven, knitted orinterconnected in another way.

The net preferably extends over all the transverse dimension of thesole. This means that the outermost part of the net is situated outsidethe limits of the foot. The part of the net situated outside the foothas a free upper side 15 a. From the free upper side 15 a there ispossibility of air H from under the foot with large humidity may beconducted out of the net and possibility of fresh air h from other partsof the footwear with lower humidity than under the foot may be conductedinto the net.

FIG. 5 shows how the air in the meshes 20 between the threads 19 istransported between the meshes 20 both longitudinally of the net andcrosswise of the net along the plane P of the net (see FIG. 4).Transportation of air occurs when the liquid-filled sole is moved eachtime the person stands or walks. The liquid in the sole is conductedbetween the different areas of the sole under the heel, the metatarsusand the ball of the foot (see FIG. 1), respectively. Movement of theliquid-filled sole imparts a kind of pumping movement to the air in thenet so that the air is transported around in the net along the plane ofthe net.

FIG. 6 shows a third embodiment where the sole comprises two nets 1,21disposed in parallel. A coarse net 1 is woven of threads 19 with athickness T and establishes a distance D between the top sheet 3 and theupper side 15 of the coarse net 1. Between the threads 19 there is adistance B defining the size of the meshes 20 between the threads 19. Afine net 21 is woven of threads 22 with a thickness t being less thanthe thickness T and establishes a distance d between the upper side 15of the coarse net 1 and an upper side 23 of the fine net 21. Between thethreads 22 is a distance b defining the size of the meshes 20 betweenthe threads 22, and which distance b is less than the distance B. Inthis embodiment there is a free upper side 23 a corresponding to thefree upper side 15 a.

The first coarsely woven net has relatively large meshes as the threadshave a relatively large thickness T and a relatively large distance Bbetween the threads. This implies that the coarse net is capable ofaccommodating relatively large amounts of air. However, since thethreads are relatively thick with a thickness T and the distance Bbetween the threads is relatively great, it will uncomfortable to treadon the coarse net as the pressure from the foot will be distributed onrelatively few threads.

Therefore a second, more finely woven net is laid on top of the coarsenet. In the fine net the diameter d of the threads is less and thedistance b between the threads is less. This means that it is morecomfortable to tread on this net as the pressure from the foot isdistributed on more and thinner threads. However, the meshes between thefibres are smaller which means that the fine net is not capable ofcontaining as much air as the coarse net. There is free access for airfrom the meshes in the fine net down to the meshes in the coarse net, sothat the total amount of air that may be contained by the coarse and thefine net is determined by the meshes in the coarse net 1 and the finenet 21 together without any separation of the meshes. Furthermore,putting the two nets together will create a greater total distance, thesum of D and d, between the top sheet and the upper side 23 of the upperfine net 23.

FIG. 7 shows a possible alternative embodiment of the net. The upperside 15,23 of the net is deformed by the threads 19,22 being pressed thedistance e downward compared with the distance D,d, and the threads arethen deformed permanently. Thereby the upper side 15,23 of each thread19,22 is flattened along a plane p, reducing the pressure from thethreads against the foot (not shown). The reduced pressure against thefoot reduces the friction and thereby heat generation when the foot ismoved and thereby displaced slightly in relation to the net 1,21. Thismeans that preparing the threads 19,22 as shown further reducesexcretion of foot perspiration and thereby increases the efficiency ofthe net.

FIG. 8 shows a further embodiment of a sole. This insole is made by amethod according to the invention as the joining takes place in twosteps. Thus the top sheet 3 and the back sheet 4 are welded together atthe edges 5 for establishing the chamber 12 containing the liquid. Inthe subsequent step, the net 1 is welded on at the edge area 5 a. Bythis embodiment it becomes possible to achieve a plane upper side 15 ofthe net simultaneously with the height 24 in the chamber 12 beingincreased compared with the above illustrated embodiments. Hereby therelief and the liquid support of the foot may be considerably increased.

The invention is described above with reference to different embodimentsof the insole according to the invention. It will be possible to makesoles where liquid-filled part of the sole has another appearance asseen in parallel with the plane of the sole where more than a singlechamber may be established between the top sheet and the back sheet andas seen perpendicularly to the plane of the sole where the top sheet andthe back sheet may have other joints than the shown transverse line andthe shown points. The net may be made of other materials than mentionedabove, as well as it is possible to use more that one or two nets.

What is claimed is:
 1. A liquid-filled insole for footwear which atleast comprises a top sheet and a back sheet between which is formed achamber containing liquid support for the foot in the footwear and inaddition comprises a cover layer disposed on top of the support, thecover layer extending at least from an area at the heel of the foot toan area at the ball of the foot in the footwear, the cover layer spacingthe support apart from the foot in the footwear, and where the coverlayer is joined with the support, wherein the cover layer is a net andthe outer edge of the net is joined with the top sheet and the backsheet, and wherein the net comprises a coarse net and a fine net, thatthe coarse net consists of threads with a given greater thickness T,that the fine net consists of threads with a given lesser thickness tless than the thickness T, and that the coarse net is disposed betweenthe top sheet and the fine net, and that the fine net is disposed on topof the coarse net.
 2. An insole according to claim 1, wherein the net atleast also extends in the whole width (W) of the sole which isdimensioned so that a free upper side is created in the part of the netlocated outside the foot.
 3. An insole according to claim 2, wherein thenet extends over all the top sheet of the whole length of the sole (L)and of the whole width (W) of the sole, and that the net is joined withboth the top sheet and the back sheet along the edges of the top sheetand the back sheet.
 4. An insole according to claim 1, wherein the netconsists of woven threads, that the threads are made of a plasticmaterial selected among PVdC, PU, EVA and PVC, and that the net and thetop sheet and the back sheet, respectively, are joined by high frequencywelding.
 5. An insole according to claim 1, wherein the net forms adistance (D,d) between the top sheet and the foot between 0.3 mm and 5.0mm.
 6. An insole according to claim 1, wherein the threads in the coarsenet has a greater mutual distance B, and that the threads in the finenet has a mutual distance b lesser than the distance B.
 7. An insoleaccording to claim 1, wherein a moisture absorbing fabric coating isprovided between the top sheet and the net.
 8. An insole according toclaim 1, wherein an upper side of the threads in the net has beendeformed for establishing a plane upper side of the threads.